In the electronics industry, it is conventional to house planar electronic devices in receiving stations in shelves of electronic equipment. Such devices include printed circuit boards carrying electronic components or circuit packs incorporating one or more of such printed circuit boards.
When removal of heat from a planar electronic device is not an important issue or is efficiently dealt with in other ways, a mounting structure is not required to be heat conductively connected to edge regions of the device and the edge regions are simply mounted in guide slots in their receiving stations. However, when it is necessary to remove heat from these edge regions, a mounting structure acts as a heat sink and pressure applying structures are placed in each guide slot at one side of an edge region of an electronic device mounted in the mounting structure. These pressure applying devices apply pressure to the one side of the edge regions so as to force the other side of the edge regions against the surface at one side of each of the guide slots whereby heat conductive engagement is acquired for conduction of heat from the devices directly into the mounting structures.
Conventionally, pressure applying structures are each formed of a large number of parts which include a plurality of sleeves arranged end-to-end in a guide slot. A threaded pin extends through the sleeve arrangement. The sleeves have inclined ends which are opposed from sleeve-to-sleeve and upon tightening of the threaded pin, axial pressure is applied to the sleeve arrangement which causes, by mutual contact between the inclined ends, relative lateral movement between adjacent sleeves. As a result the sleeve arrangement expands in a radial direction so as to apply pressure against the one side of an edge region as discussed above. However, this pressure is only applied by the contact of alternate sleeves against an edge region of an electronic device with the result that while intense pressure is applied through the edge region in alignment which each of the alternate sleeves, direct pressure is not applied to the lengths of the edge region between these alternate sleeves. As a consequence, slight undulation in an edge region may result whereby continuous heat conductive pressure is not applied for the full length of the edge region thereby limiting the heat conductive efficiency between edge region and mounting structure. Thus, conventional pressure applying structures are severely limited in their capability to effect high efficiency heat transfer from a planar electronic device through edge regions of the device into a mounting structure. In addition to this, there is a further disadvantage in that such pressure applying structures in employing a large number of parts which are precisely made, are extremely expensive to manufacture and assemble and of course are not of simple design.
Another known method of creating heat conductive contact between an edge region and an electronic device, an elongated cam is rotated within a slot for the purpose of providing lateral pressure to an edge region of an electronic device to create the heat conductive contact required. However, this solution is also expensive to produce and requires high precision machine parts.